Wow. Thank you so much for this post! I always thought I was flipping crazy, but it actually makes sense now!
As an aside, I just went ahead and bit the bullet and got a new laptop as I was under the impression the CPU was very power hungry, and that no matter what upgrades I gave it, it would never be "efficient" enough for me to use for what I need a laptop for, which is battery life.
Thank you for helping me understand the issue was always there, and that I should've definitely researched more before I bought these upgrades!
I've realized, thanks to tal, that I was under the wrong impression and had thought the CPU was just too power hungry. Maybe it is, but it has always had not so good battery life unfortunately.
I have bitten the bullet, and upgraded to a newer laptop. The battery actually lasts multiple days of youtube, plex, and anything else like games I throw at it. I just wanted a laptop I didn't have to worry about charging unless I got a few uses out of it first! I will always miss the glowing apple on the back of the lid though. That was some good times. :')